Immune thrombocytopenia (ITP) occurs when the immune system attacks and destroys healthy platelets. A person who has ITP is more likely to bruise or bleed.

Thrombocytopenia means a person does not have enough of a type of blood cell that helps with blood clotting, called platelets. This can happen when someone has another autoimmune disease, a viral infection, or certain cancers. It can also happen due to certain medications.

People of all ages can develop ITP, but it is most common in children and older adults. Females are more likely to develop ITP than males.

This article discusses ITP symptoms and causes, as well as diagnosis and treatment.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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ITP is an immune condition in which the body does not have enough platelets. Platelets are cells that help the blood to clot — without enough of them, a person is at risk for excessive bleeding.

ITP can cause marks known as purpura on the skin, which may look like small, red dots. These are the result of tiny blood vessels leaking due to low platelet levels.

ITP can also cause bleeding, such as nosebleeds, heavy periods, or gastrointestinal bleeding. However, around 1 in 3 newly diagnosed people have no bleeding.

Doctors classify ITP as “newly diagnosed” when a person has had the condition for less than 3 months. ITP is “persistent” when present for 3–12 months and “chronic” if someone has it for more than 1 year.

ITP can have a range of symptoms, from none at all to life threatening bleeding. Many people with ITP only have mild symptoms and do not require treatment.

The most common symptoms include:

The causes of ITP vary depending on whether a person has primary or secondary ITP.

In all cases of ITP, the immune system attacks and destroys healthy platelets. In primary ITP, the condition occurs on its own and has no clear or single cause. A combination of genetic and environmental factors may contribute.

In secondary ITP, the condition develops as a knock-on effect of something else, such as another medical condition. Diseases that can cause secondary ITP include:

The presence of Helicobacter pylori bacteria also has links to ITP, but studies have not yet confirmed whether it causes the condition. However, in a 2021 study, treatment for H. pylori also helped to improve ITP in 58.7% of participants. More research is necessary to explore the link.

In children, secondary ITP often develops after a viral infection. This can happen whether the infection was mild or severe. For example, it could develop after chickenpox, the common cold, or COVID-19.

Rarely, ITP develops after a child gets a vaccination, such as the measles, mumps, and rubella (MMR) vaccine. Doctors have also reported some cases of ITP following the COVID-19 vaccine.

However, this is very unlikely. As any of these viral infections could also cause ITP, as well as severe illness, the benefits of vaccination generally outweigh the risk.

A person of any age can develop ITP, but it is more prevalent in older adults aged 60 years and over and in children under 10 years.

Children in this age group account for 4 in 10 of all ITP cases, particularly after they have had a viral illness such as chickenpox, mumps, or measles.

Other risk factors include:

  • Family history and genetics: A person with mutations or changes in the genes that control platelet production has a higher chance of developing ITP.
  • Lifestyle habits: Drinking alcohol, using tobacco, and eating certain foods such as walnuts and sesame seeds may increase ITP risk.
  • Medications: These include certain over-the-counter pain medications, antibiotics, blood thinners, chemotherapy, radiation therapy, immunosuppressants, seizure medications, and stomach acid (H2) blockers.
  • Health conditions: HIV-associated disease is the most common cause of ITP, particularly in males aged 20–50 years. Vitamin B12 deficiency, anemia, blood and bone marrow diseases, kidney disease, and liver disease may also make a person more likely to develop ITP.
  • Sex: People with female biology are more at risk for platelet disorders than males.

ITP is a diagnosis of exclusion, meaning that doctors rule out other potential causes of low platelet counts before arriving at the ITP diagnosis.

They will take a full medical history and order blood tests to check the following:

They may also use tests to assess how well a person’s bone marrow works if they identify a low platelet count. In ITP, bone marrow is usually normal.

Many people with ITP do not require treatment. They may have mild symptoms, or the disorder may resolve on its own.

For those who do require treatment or have persistent ITP, the main treatment goals are to prevent or stop bleeding and to keep platelet levels above a safe threshold. The options include:

  • Corticosteroids: These anti-inflammatory drugs help suppress the immune system.
  • Immunoglobulins: These are antibodies that help the immune system function properly. Doctors deliver them intravenously into a vein.
  • Rituximab (Rituxan): This is a monoclonal antibody that targets and binds to B-cells, which are a type of immune cell. This reduces the number of cells that can make proteins to attack platelets.
  • Thrombopoietin receptor agonists: These drugs boost platelet production in the bone marrow.

Doctors may also recommend transfusions of platelets or of whole blood to people who are currently bleeding or who are at high risk.

For people with chronic ITP that does not respond to standard treatment, doctors may suggest a splenectomy, which is the surgical removal of the spleen. The spleen is responsible for removing old platelets from the blood, so its removal can help increase platelet counts.

A doctor may suggest certain lifestyle changes to help a person manage ITP. These may include:

ITP can cause bleeding in different parts of the body. Rarely, it can lead to more serious bleeding, such as bleeding in the brain, which can be life threatening.

Treatments can also lead to complications. For example, taking corticosteroids for a long time can lead to osteoporosis and an increased risk of infection.

Living without a spleen also increases the risk of bacterial infections and can increase illness severity. Therefore, people who undergo this surgery must look after their health carefully and contact a doctor as soon as possible if they develop a fever or other symptoms.

ITP is a disorder that occurs when the immune system destroys healthy platelets, resulting in low platelet levels. Platelets help the blood to clot, so low levels can lead to bleeding and bruising in different parts of the body. However, not everyone with ITP has noticeable symptoms.

ITP can resolve on its own, but some people require treatments, such as corticosteroids or immunoglobulins. In some cases, doctors may suggest surgery to remove the spleen.

ITP can lead to serious complications if left untreated, but many people can manage it with lifestyle changes and medical care.